1. Field of the Invention
The present Invention relates to a follow-up slotting tool suitable for use to form an elongate slot, for instance by punching off workpiece continuously and repeatedly by feeding plate material by a predetermine pitch. Here, the follow-up implies that a plurality of residues (punched-off parts of workpiece) are each cut partially and then completely away from workpiece continuously to form an elongate slot, without forming any stepped portions at the junction portions in the punched-off plate material.
2. Description of the Related Art
As the conventional follow-up slotting tools for continuously punching off workpiece located and shifted between a punch and a die to form an elongate slot, for instance, there have been so far known an elongated rectangular punch and a slotting tool (as disclosed in Japanese Published Unexamined Utility Model Application (Kokai) No. 2-76621). In the case of the conventional elongated rectangular punch, however, since stepped (non-straight) portions are inevitably formed at the junction (overlap-punched) portions of the punched-off workpiece, whenever excellent external appearance is required for the punched-off products, it has been so far necessary of finish or eliminate the formed stepped portions with the use of a file, for instance.
Further, in the case of the conventional slotting tool, although no stepped portions are formed, since the slotting tool is provided with vertically movably tip and pin and a cam mechanism for driving the tip and pin, there exist problems in that the die mechanism is complicated; work feed pitch is small; and a long processing time is required. In addition, since there exists a limit of the cutting length punched off by the slotting tool, another problem arises in that the junction portions are inevitably formed at several positions of the workpiece in the case where a relatively long slot is required to be formed.